/* 程序11-10 将终端方式设置为原始或cbreak方式 */
#include <termios.h>
#include <unistd.h>

static struct termios save_termios;
static int ttysavefd = -1;
static enum { RESET, RAW, CBREAK } ttystate = RESET;

int tty_cbreak(int fd)		/* put terminal into a cbreak mode */
{
	struct termios buf;

	if (tcgetattr(fd, &save_termios) < 0)
		return(-1);

	buf = save_termios;		/* structure copy */

	buf.c_lflag &= ~(ECHO | ICANON);
							/* echo off, canonical mode off */
	buf.c_cc[VMIN] = 1;		/* Case B: 1 byte at a time, no timer */
	buf.c_cc[VTIME] = 0;

	if (tcsetattr(fd, TCSAFLUSH, &buf) < 0)
		return(-1);
	ttystate = CBREAK;
	ttysavefd = fd;
	return(0);
}

int tty_raw(int fd)		/* put terminal into a raw mode */
{
	struct termios buf;

	if (tcgetattr(fd, &save_termios) < 0)
		return(-1);

	buf = save_termios;		/* structure copy */

	buf.c_lflag &= ~(ECHO | ICANON | IEXTEN | ISIG);
							/* echo off, canonical mode off, extended input
								processing off, signal chars off */

	buf.c_iflag &= ~(BRKINT | ICRNL | INPCK | ISTRIP | IXON);
							/* no SIGINT on BREAK, CR-to-NL off, input parity
								check off, don't strip 8th bit on input,
								ontput flow control off */

	buf.c_cflag &= ~(CSIZE | PARENB);
							/* clear size bits, parity checking off */
	buf.c_cflag |= CS8;
							/* set 8 bits/char */

	buf.c_oflag &= ~(OPOST);
							/* output processing off */

	buf.c_cc[VMIN] = 1;		/* Case B: 1 byte at a time, no timer */
	buf.c_cc[VTIME] = 0;

	if (tcsetattr(fd, TCSAFLUSH, &buf) < 0)
		return(-1);
	ttystate = RAW;
	ttysavefd = fd;
	return(0);
}

int tty_reset(int fd)		/* restore terminal's mode */
{
	if (ttystate != CBREAK && ttystate != RAW)
		return(0);

	if (tcsetattr(fd, TCSAFLUSH, &save_termios) < 0)
		return(-1);
	ttystate = RESET;
	return(0);
}

void tty_atexit(void)		/* can be set up by atexit(tty_atexit) */
{
	if (ttysavefd >= 0)
		tty_reset(ttysavefd);
}

struct termios *tty_termios(void)	/* let caller see original tty state */
{
	return(&save_termios);
}
	
